GCVSPLUtil.h

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#ifndef SimTK_SIMMATH_GCVSPL_UTIL_H_
#define SimTK_SIMMATH_GCVSPL_UTIL_H_

/* -------------------------------------------------------------------------- *
 *                      SimTK Core: SimTK Simmath(tm)                         *
 * -------------------------------------------------------------------------- *
 * This is part of the SimTK Core biosimulation toolkit originating from      *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org.               *
 *                                                                            *
 * Portions copyright (c) 2008 Stanford University and the Authors.           *
 * Authors: Peter Eastman                                                     *
 * Contributors:                                                              *
 *                                                                            *
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 * copy of this software and associated documentation files (the "Software"), *
 * to deal in the Software without restriction, including without limitation  *
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 * and/or sell copies of the Software, and to permit persons to whom the      *
 * Software is furnished to do so, subject to the following conditions:       *
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 * The above copyright notice and this permission notice shall be included in *
 * all copies or substantial portions of the Software.                        *
 *                                                                            *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR *
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,   *
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL    *
 * THE AUTHORS, CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,    *
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR      *
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE  *
 * USE OR OTHER DEALINGS IN THE SOFTWARE.                                     *
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#include "SimTKcommon.h"
#include "simmath/internal/common.h"

int gcvspl_(const SimTK::Real *, const SimTK::Real *, int *, const SimTK::Real *, const SimTK::Real *, int *, int *,
            int *, int *, SimTK::Real *, SimTK::Real *, int *, SimTK::Real *, int *);
SimTK::Real splder_(int *, int *, int *, SimTK::Real *, const SimTK::Real *, const SimTK::Real *, int *, SimTK::Real *, int);

namespace SimTK {

class SimTK_SIMMATH_EXPORT GCVSPLUtil {
public:
    template <int K>
    static void gcvspl(const Vector& x, const Vector_<Vec<K> >& y, const Vector& wx, Vec<K> wy, int m, int md, Real val, Vector_<Vec<K> >&c, Vector& wk, int& ier);
    template <int K>
    static Vec<K> splder(int derivOrder, int degree, Real t, const Vector& x, const Vector_<Vec<K> >&coeff);
};

template <int K>
void GCVSPLUtil::gcvspl(const Vector& x, const Vector_<Vec<K> >& y, const Vector& wx, Vec<K> wy, int degree, int md, Real val, Vector_<Vec<K> >&c, Vector& wk, int& ier) {
    SimTK_APIARGCHECK_ALWAYS(degree > 0 && degree%2==1, "GCVSPLUtil", "gcvspl", "degree must be positive and odd");
    SimTK_APIARGCHECK_ALWAYS(y.size() >= x.size(), "GCVSPLUtil", "gcvspl", "y is shorter than x");
    SimTK_APIARGCHECK_ALWAYS(wx.size() >= x.size(), "GCVSPLUtil", "gcvspl", "wx and x must be the same size");
    SimTK_APIARGCHECK_ALWAYS(x.hasContiguousData(), "GCVSPLUtil", "gcvspl", "x must have contiguous storage (i.e. not be a view)");
    SimTK_APIARGCHECK_ALWAYS(wk.hasContiguousData(), "GCVSPLUtil", "gcvspl", "wk must have contiguous storage (i.e. not be a view)");
    
    // Create various temporary variables.
    
    int m = (degree+1)/2;
    int n = x.size();
    int ny = y.size();
    Vector yvec(ny*K);
    int index = 0;
    for (int j = 0; j < K; ++j)
        for (int i = 0; i < ny; ++i)
            yvec[index++] = y[i][j];
    int nc = n*K;
    Vector cvec(nc);
    wk.resize(6*(m*n+1)+n);
    int k = K;
    
    // Invoke GCV.
    
    gcvspl_(&x[0], &yvec[0], &ny, &wx[0], &wy[0], &m, &n, &k, &md, &val, &cvec[0], &n, &wk[0], &ier);
    if (ier != 0) {
        SimTK_APIARGCHECK_ALWAYS(n >= 2*m, "GCVSPLUtil", "gcvspl", "Too few data points");
        SimTK_APIARGCHECK_ALWAYS(ier != 2, "GCVSPLUtil", "gcvspl", "The values in x must be strictly increasing");
        SimTK_APIARGCHECK_ALWAYS(ier == 0, "GCVSPLUtil", "gcvspl", "GCVSPL returned an error code");
    }
    c.resize(n);
    index = 0;
    for (int j = 0; j < K; ++j)
        for (int i = 0; i < n; ++i)
            c[i][j] = cvec[index++];
}

template <int K>
Vec<K> GCVSPLUtil::splder(int derivOrder, int degree, Real t, const Vector& x, const Vector_<Vec<K> >&coeff) {
    assert(derivOrder >= 0);
    assert(t >= x[0] && t <= x[x.size()-1]);
    assert(x.size() == coeff.size());
    assert(degree > 0 && degree%2==1);
    assert(x.hasContiguousData());
    
    // Create various temporary variables.
    
    Vec<K> result;
    int m = (degree+1)/2;
    int n = x.size();
    int interval = (int) ceil(n*(t-x[0])/(x[n-1]-x[0]));
    Vector_<double> q(2*m);
    int offset = (int) (&coeff[1][0]-&coeff[0][0]);

    // Evaluate the spline one component at a time.
    
    for (int i = 0; i < K; ++i)
        result[i] = splder_(&derivOrder, &m, &n, &t, &x[0], &coeff[0][i], &interval, &q[0], offset);
    return result;
}

} // namespace SimTK

#endif // SimTK_SIMMATH_GCVSPL_UTIL_H_